This invention relates to parenteral administration sets, and more particularly, to an intravenous set for administering fluids intravenously.
Even more specifically, the present invention relates to a disposable intravenous administration set including a drip chamber of substantially conventional construction having means theron for connection with a source of IV fluid, a length of flexible IV tubing connected with the drip chamber, valve means in the length of tubing operable from exteriorly of the tubing to open and closed positions to obtain a desired drip rate through the drip chamber and thus obtain a desired flow rate through the set, and wherein a fixed restrictor is in the length of tubing to impart a predetermined back pressure to flow therethrough to thus regulate, at least to an extent, the time it takes a drop to form in the drip chamber and thereby insure that only one drop will form and fall for each cycle of valve operation, at least for normal operating ranges, and preferably from about 1 drop per minute up to about 99 drops per minute.
In the prior art, many different types of intravenous and parenteral administration sets are known. Many such sets are controlled by valve means, and some even have internal valve means. However, with the prior art intravenous administration sets, there is no means provided to regulate the rate of drop formation to insure that only one drop will form and fall during the time that the control valve is open. In other words, it is frequently necessary to use different needle sizes, depending upon th type of fluid being administered and the urgency with which a prescribed amount of fluid must be introduced into a patient's veins, and if the size or gauge of the needle used is no larger than about 20 or 21 gauge, the rate of drop formation will be regulated so that only one drop will form and fall for each opening cycle of the valve, so long as the valve cycle is within normal operating ranges.
However, when a larger bore needle is used with the prior art sets, there is practically no back pressure on the system, and the set is operating essentially as an open flow set, and accordingly, when the valve opens, there is no regulation of the rate of drop formation and more than one drop may form and fall during the time the valve is open. Accordingly, accurate regulation of drop rate and thus flow rate through the prior art sets cannot be obtained with all needle sizes likely to be used with the set.
With the present invention, having the unique internal valve and fixed restrictor, as noted above, the rate of drop formation is regulated due to the back pressure imposed on the system by the restrictor, and accordingly, the rate of drop formation is such that only one drop will form and fall during a cycle of operation of the valve regardless of the size of needle used on the set.